Thanks, Flynn. I’ve done a little further digging and that African origin would tie in with this site,

THE DOWNFALL OF PREMPEH, A DIARY OF LIFE WITH THE NATIVE LEVY IN ASHANTI 1895-96 By Major R. S. S. Baden-Powell 13th Hussars, Commanding The Native Levy.

........ If it were not for the depressing heat and the urgency of the work, one could sit down and laugh to tears at the absurdity of the thing, but under the circumstances it is a little “wearing.” But our motto is the old West Coast proverb, “Softly, softly, catchee monkey”; in other words, “Don’t flurry; patience gains the day.” It was in joke suggested as a maxim for our levy of softly-sneaking scouts, but we came to adopt it as our guiding principle, and I do not believe that a man acting on any other principle could organise a native levy on the West Coast—and live. ..........

I wonder if this is the first appearance in English of the proverb. Presumably BP wrote this in 1895/6 but there’s no indication there of when it was published.

Good work, John, and welcome too! And thanks for showing me how to search google books within date parameters. Using my new-found skill, I might have found an answer to aldi’s question about where it comes from. Also from google books, courtesy of The Works of Jonathan Swift, Dublin 1757, though the poem appears to have been written in 1730:

Sly hunters thus, in Borneo’s isle,
To catch a monkey by a wile,
The mimic animal amuse;
They place before him gloves and shoes;
Which, when the brute puts awkward on,
All his agility is gone:
In vain to frisk or climb he tries;
The huntsmen seize the grinning prize.

Although it doesn’t mention “softly softly”, it relates to a place where pidgin English was spoken and to the guile needed to catch a monkey.

Just for general reference, Google Books is filled with misdatings and misfilings. You absolutely cannot trust the dates that searching Google Books turns up. You must verify the date on the title page of the publication and also make sure that the page you are citing is actually from the same work listed on the title page. Google Books is also filled with works that have been mashed together (not unlike medieval codices which would contain several works written at different times in one binding).

And Panda cars not a protected species? Underpowered Ford Escorts with ner-ner sirens and ossifers in slightly less silly hats than the bobby on the beat!
Tooled-up Capris. Leave it out, George. ‘E’s got a shooter, guv! Gritty realism arrives.